HomeMy WebLinkAboutStormwater Calculations 01-14-25Stormwater Calculations
North End Phase 2
Prepared:
January 14, 2024
By:
CrossRoad Engineers, PC
115 N 17th Avenue
Beech Grove, IN 46107
Phone No.: (317) 780-1555
Email: cmattox@crossroadengineers.com
115 N 17th AVENUE, BEECH GROVE, IN 46107 // 317.780.1555 // CROSSROADENGINEERS.COM PAGE 2 of 6
Section 1: Stormwater Calculations Summary
Pre-Development Conditions
The project site is situated on approximately 10.4 acres and will be Phase 2 of the overall North End
development. The project is located just northeast of North End Phase 1 at northeast corner of
Smoky Row Road and US31 in Carmel, IN. There will also be an offsite pond serving a separate
development that will be over-detained to serve the needs of this development. That site is located
at 2911 E Smoky Row Road in Carmel, IN. See the included project location maps in this section.
The southeast corner of the site falls within floodplain limits identified by the Community Panel
#18057C0207G of the Flood Insurance Rate Map dated 11-19-14. The map is included in this section.
A portion of the development will fill above the BFE within the floodplain limits. The mitigation will
take place directly east of the site, and grading of this area is included in the construction plan
documents.
Post-Development Conditions
This project includes the construction of 72 residential units in 8-,12-, and 16-unit buildings, and a
55 and over development (Lot 2) in the northeast portion of the site. An onsite storm sewer system
will collect and convey runoff to the southeast corner of the site to cool creek tributary. See Exhibit
1 for the Post-Developed Conditions.
Storm Sewer Design
The proposed onsite storm sewer network is designed to accommodate a 10-year storm event. The
Rational Method was used to perform the storm sewer pipe sizing calculations. Structures and
grates were designed and placed so that the depth of ponding above the inlet does not exceed 6
inches at half blocked condition.
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MARANA DR
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Project Location Map
Parcels
Street Ownership
Carmel
Private
INDOT
Aerial Photography
Red: Red
Green: Green
Blue: Blue
1/14/2025, 2:22:21 PM
0 0.06 0.110.03 mi
0 0.09 0.180.04 km
1:3,000
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WILLOWICK RD
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Offsite Pond Location
Parcels
Street Ownership
Carmel
Aerial Photography
Red: Red
Green: Green
Blue: Blue
1/14/2025, 2:23:41 PM
0 0.06 0.110.03 mi
0 0.09 0.180.04 km
1:3,000
DDAB
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WAY
EXHIBIT 1 - POST-DEVELOPED CONDITIONS
NOT TO SCALE
ONSITE BASIN
AREA = 8.19 AC
CN = 90
US 3
1
NORTH END PHASE 2
PHASE 1
115 N 17th AVENUE, BEECH GROVE, IN 46107 // 317.780.1555 // CROSSROADENGINEERS.COM PAGE 3 of 6
Section 2: Hydrologic Modeling Calculations & Detention Calculations
All drainage calculations were completed and modeled using Autodesk Hydraflow Extension. The
SCS Curvilinear method utilizing the Type II rainfall distribution was used to calculate the
hydrographs. The TR-55 Method was used to calculate times of concentration. Curve numbers
were computed based on the applicable land use and the percentage by area of each hydrologic
soil type obtained from the USGS Soil Web Survey. The soil map and the rating of the existing soils
is included in this section.
Runoff Curve Number Calculations
Pre-Development Runoff Curve Number Calculations
Post Developed Onsite Basin
Land Use Description
Runoff Curve No. For
Hydrologic Group –
Average
Runoff Curve
Number Percentage Used* 100%
Pasture/Good
Condition 72 (2.51 acres) 72
Impervious 98 (5.68 acres) 98
Overall Post-Developed Curve Number 90
Post-Development Runoff Curve Number Calculations
Post-Developed Offsite Basin
Land Use Description
Runoff Curve No. For
Hydrologic Group – D
Average
Runoff
Curve
Number Percentage Used* 100%
Single Fam Lots,
Offsite Basin 1 84 (9.89 acres) 84
Single Fam Lots
Offsite East 84 (1.59 acres) 84
Commercial
Offsite West 95 (2.30 acres) 95
Overall Post-Developed Curve Number 86
Hydrologic Soil Group—Hamilton County, Indiana
(North End Phase 2 Soil Map)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
3/16/2022
Page 1 of 4
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573850 573900 573950 574000 574050 574100 574150 574200
573850 573900 573950 574000 574050 574100 574150 574200
39° 59' 21'' N
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39° 59' 6'' N
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Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 16N WGS84
0 100 200 400 600
Feet
0 30 60 120 180
Meters
Map Scale: 1:2,320 if printed on A portrait (8.5" x 11") sheet.
Soil Map may not be valid at this scale.
Hydrologic Soil Group
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
YclA Crosby silt loam, fine-
loamy subsoil-Urban
land complex, 0 to 2
percent slopes
C/D 0.1 0.7%
YmsB2 Miami silt loam-Urban
land complex, 2 to 6
percent slopes,
eroded
C 3.2 31.3%
YmsC2 Miami silt loam-Urban
land complex, 6 to 12
percent slopes,
eroded
C 5.8 56.1%
YmsD2 Miami silt loam-Urban
land complex, 12 to
18 percent slopes,
eroded
C 0.1 1.3%
YshAH Shoals silt loam-Urban
land complex, 0 to 2
percent slopes,
frequently flooded,
brief duration
B/D 1.1 10.7%
Totals for Area of Interest 10.4 100.0%
Hydrologic Soil Group—Hamilton County, Indiana North End Phase 2 Soil Map
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
3/16/2022
Page 3 of 4
Hydrologic Soil Group—Hamilton County, Indiana
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
1/14/2025
Page 1 of 4
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575620 575670 575720 575770 575820 575870 575920 575970 576020 576070
575620 575670 575720 575770 575820 575870 575920 575970 576020 576070
39° 59' 9'' N
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Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 16N WGS84
0 100 200 400 600
Feet
0 30 60 120 180
Meters
Map Scale: 1:2,170 if printed on A landscape (11" x 8.5") sheet.
Soil Map may not be valid at this scale.
Hydrologic Soil Group
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
YbvA Brookston silty clay
loam-Urban land
complex, 0 to 2
percent slopes
B/D 3.4 22.0%
YmsB2 Miami silt loam-Urban
land complex, 2 to 6
percent slopes,
eroded
C 7.8 50.8%
YmsD2 Miami silt loam-Urban
land complex, 12 to
18 percent slopes,
eroded
C 3.9 25.3%
YshAH Shoals silt loam-Urban
land complex, 0 to 2
percent slopes,
frequently flooded,
brief duration
B/D 0.3 1.8%
Totals for Area of Interest 15.4 100.0%
Hydrologic Soil Group—Hamilton County, Indiana
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
1/14/2025
Page 3 of 4
115 N 17th AVENUE, BEECH GROVE, IN 46107 // 317.780.1555 // CROSSROADENGINEERS.COM PAGE 4 of 6
Detention Calculations:
The City of Carmel requires a detention design that outlets stormwater at the following rates:
Post-Development: Pre-Development:
Post 10-yr Q ≤ 0.1 cfs / acre
Post 100-yr Q ≤ 0.3 cfs / acre
The developer has coordinated the proposed detention methodology with the City of Carmel, and
the impact of North End Phase 2 is to be offset by the over-detaining of another proposed
development downstream that also ultimately drains to Cool Creek. The methodology is such that
the proposed development at 2911 E Smoky Row Rd, which will be subdivided into single-family
lots, will be restricted significantly more than required. The developer intends to capture as much
additional runoff from adjacent properties as possible to further assist in offsetting the impact of
North End Phase 2. As can be seen on Exhibit 2 there is an offsite contribution to this property from
the east. Rather than redirecting or allowing the runoff to flow through the pond, it has been
included in the detention volume models. In addition, the property to the west directly discharges
to Cool Creek, and the developer intends to allow for this property to discharge to the proposed
wet pond as well.
In order to determine the volume needed to offset North End Phase 2, a modified rational method
calculation was done to determine what volume must be detained over and above the
requirements for 2911 E Smoky Row Road. This calculation calls for 1.25 additional acre-ft (54,450
cft) of storage to be realized by this development.
Two model scenarios are included in this report. The first serves to act as the control model, where
the pond was designed as is typically required to meet the allowable release rates. Using a single
12” orifice, the proposed release for this scenario is as follows:
100-year – 3.05 cfs < 4.13 cfs allowable (10.23 acres x 0.3 cfs/acre)
The second scenario restricts the pond more significantly using a single 3” orifice. The proposed
release for this scenario is as follows:
100-year – 0.41 cfs < 4.13 cfs allowable (10.23 acres x 0.3 cfs/acre)
The analysis shows that the over-detained scenario holds back an additional 65,221 cft (232,080 cft
vs. 166,859 cft) of runoff for the duration and restricts the pond release rate by an additional 86%.
This is more than enough volume to offset the 54,450 cft required per the North End calculation.
An emergency spillway shall be provided to pass 1.25 times the Q100 of all contributing watersheds
in the event the detention outlet structure becomes plugged and/or overwhelmed. The spillway
was sized to accommodate the 117 cfs contributing flow.
Peak Flowrate = 117 cfs
Length of Weir, L = 80 ft.
Spillway Crest Elevation = 799.27
Max. Head, H = 0.6 ft.
Top of Bank = 802.00
Freeboard = 2.13 ft
EXHIBIT 2 - OFFSITE POND EXHIBIT
NOT TO SCALE
OFFSITE BASIN 1
AREA = 9.89 AC
CN = 84
NORTH END PHASE 2
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AREA = 2.30 AC
CN = 95
OFFSITE
EAST
A = 1.59 AC
CN = 84
E SMOKY ROW R
D
DETENTION STORAGE CALCULATIONS
Project:North End Ph 2
Design Return Period 100 yrs
Time of Concentration 30.00 min.Watershed Area, (AD)8.19 acres
(Undeveloped Watershed)(Developed Watershed)
Rainfall Intensity, (iU)3.25 in./hr Developed Runoff 0.64
Coefficient, (CD)
Release Rate 2.46 cfs
(Total area, North End + 2911 E Smoky x 0.3 cfs/acre)
Storm Rainfall Inflow Outflow Storage Required
Duration Intensity Rate Rate Rate Storage
td id I(td) =O =I(td)-O [I(td)-O]*td/12
C x Ix A 0.3cfs/acre
(hrs)(in./hr)(cfs)(cfs)(cfs)(acre-ft)
0.08 9.12 47.80 2.46 45.34 0.30
0.17 7.78 40.78 2.46 38.32 0.54
0.25 6.77 35.49 2.46 33.03 0.69
0.50 4.84 25.37 2.46 22.91 0.95
1.00 3.03 15.88 2.46 13.42 1.12
2.00 1.87 9.80 2.46 7.34 1.22
3.00 1.42 7.44 2.46 4.98 1.25
6.00 0.85 4.46 2.46 2.00 1.00
12.00 0.48 2.52 2.46 0.06 0.06
24.00 0.27 1.42 2.46 -1.04 -2.09
Weir Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Tuesday, Jan 14 2025
Emergency Spillway
Trapezoidal Weir
Crest = Sharp
Bottom Length (ft) = 80.00
Total Depth (ft) = 2.00
Side Slope (z:1) = 3.00
Calculations
Weir Coeff. Cw = 3.10
Compute by: Known Q
Known Q (cfs) = 117.00
Highlighted
Depth (ft) = 0.60
Q (cfs) = 117.00
Area (sqft) = 49.08
Velocity (ft/s) = 2.38
Top Width (ft) = 83.60
0 10 20 30 40 50 60 70 80 90 100 110 120
Depth (ft) Depth (ft)Emergency Spillway
-1.00 -1.00
0.00 0.00
1.00 1.00
2.00 2.00
3.00 3.00
Length (ft)Weir W.S.
115 N 17th AVENUE, BEECH GROVE, IN 46107 // 317.780.1555 // CROSSROADENGINEERS.COM PAGE 5 of 6
Section 3: Pipe Sizing Calculations
The Rational Method was used to size the pipes to convey the peak runoff from the 10-year storm.
A minimum time of concentration of 5 minutes was used. The pipe sizing calculations, inlet basin
map, and time of concentration worksheets are included within this section.
DDAB
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EXHIBIT 3 - INLET BASIN MAP
NOT TO SCALE
US 3
1
NORTH END PHASE 2
PHASE 1
STR 1
STR 2
STR 3
STR 4
STR 5
STR 6
STR 7
STR 8
STR 9
STR 10
STR 11
STR 12
STR 13
STR 14
STR 15
STR 16
STR 17
STR 18
STR 19 STR 20
Pipe and Inlet Sizing Calculations
Downstream
Structure
Length
(ft)
Pipe
Diameter
(in)
Pipe
Material
Invert
Slope
(%)
Mannings
Number n
Catchment
Area (ac)
Roof
Runoff
Coefficient
C Roof
Catchment
Area (ac)
Grass
Runoff
Coefficient
C Grass
Catchment
Area (ac)
Impervious
Runoff
Coefficient
C
Impervious
Total
Area
A
(ac)
Composite
Coefficient
C
Tc
(min)
Rainfall
Intensity
(i) in/hr
Manual
Input Flow
Q
(cfs)
Q=CiA
(cfs)
Total
Area
A
(ac)
Runoff
Coefficient
C
Time in
Upstream
Pipe (min)
Total Time of
Concentration
Tc (min)
Intensity
I
(in/hr)
Total
Pipe
Flow
(cfs)
Pipe
Capacity
Qmax
(cfs)
Pipe
Velocity
(ft/s)
% of Full
Flow
Capacity
STR 1 STR 2 123 12 RCP 0.31 0.013 0.02 0.90 0.03 0.20 0.25 0.85 0.30 0.79 10.00 5.22 --1.23 0.30 0.79 N/A 10.00 5.22 1.23 1.98 2.52 62%
STR 2 STR 3 130 12 RCP 0.50 0.013 0.02 0.90 0.03 0.20 0.12 0.85 0.17 0.74 10.00 5.22 --0.66 0.47 0.77 0.81 10.81 5.11 1.85 2.51 3.20 74%
STR 3 STR 4 81 12 RCP 0.50 0.013 0.03 0.90 0.03 0.20 0.08 0.85 0.14 0.72 10.00 5.22 --0.53 0.61 0.76 0.68 11.49 5.02 2.33 2.51 3.20 93%
STR 4 STR 5 97 24 RCP 0.75 0.013 0.03 0.90 0.11 0.20 0.17 0.85 0.31 0.62 10.00 5.22 --1.01 6.52 0.54 0.19 12.57 4.76 16.63 19.60 6.24 85%
STR 5 STR 6 100 24 RCP 0.75 0.013 0.02 0.90 0.06 0.20 0.15 0.85 0.23 0.68 10.00 5.22 --0.82 6.75 0.54 0.26 12.83 4.74 17.31 19.60 6.24 88%
STR 6 STR 7 69 24 RCP 0.80 0.013 0.03 0.90 0.08 0.20 0.16 0.85 0.27 0.66 10.00 5.22 --0.93 7.02 0.55 0.27 13.10 4.71 18.04 20.24 6.44 89%
STR 7 STR 8 129 24 RCP 0.90 0.013 0.04 0.90 0.14 0.20 0.18 0.85 0.36 0.60 10.00 5.22 --1.13 7.38 0.55 0.18 13.28 4.70 19.03 21.47 6.83 89%
STR 8 STR 9 153 30 RCP 0.50 0.013 0.05 0.05 0.09 0.20 0.19 0.85 0.33 0.68 10.00 5.22 --1.17 8.87 0.54 0.31 13.59 4.67 22.46 29.04 5.92 77%
STR 9 STR 10 91 30 RCP 0.50 0.013 0.13 0.13 0.09 0.20 0.33 0.85 0.55 0.76 10.00 5.22 --2.17 9.42 0.55 0.43 14.02 4.63 24.19 29.04 5.92 83%
STR 10 END 53 30 RCP 0.50 0.013 0.02 0.02 0.02 0.20 0.09 0.85 0.13 0.76 10.00 5.22 --0.51 9.55 0.56 0.26 14.28 4.61 24.54 29.04 5.92 85%
STR 11 STR 12 60 12 RCP 0.31 0.013 0.06 0.06 0.13 0.20 0.27 0.85 0.46 0.67 10.00 5.22 --1.62 0.46 0.67 N/A 10.00 5.22 1.62 1.98 2.52 82%
STR 12 STR 13 147 15 RCP 0.25 0.013 0.03 0.03 0.04 0.20 0.13 0.85 0.20 0.73 10.00 5.22 --0.76 0.66 0.69 0.40 10.40 5.17 2.35 3.23 2.63 73%
STR 13 STR 15 161 15 RCP 0.75 0.013 0.20 0.20 0.08 0.20 0.32 0.85 0.60 0.78 10.00 5.22 --2.44 1.26 0.73 0.93 11.33 5.04 4.65 5.59 4.55 83%
STR 14 STR 15 85 24 RCP 0.30 0.013 0.00 0.00 3.54 0.20 0.79 0.85 4.33 0.32 30.00 3.25 --4.48 4.33 0.32 N/A 30.00 3.25 4.48 12.40 3.95 36%
STR 15 STR 16 143 24 RCP 0.50 0.013 0.08 0.08 0.07 0.20 0.30 0.85 0.45 0.76 10.00 5.22 --1.78 5.59 0.47 0.59 11.92 5.22 13.80 16.00 5.09 86%
STR 16 STR 4 62 24 RCP 0.60 0.013 0.00 0.00 0.12 0.20 0.20 0.85 0.32 0.61 10.00 5.22 --1.01 5.91 0.48 0.47 12.39 4.78 13.56 17.53 5.58 77%
STR 17 STR 18 90 15 RCP 0.50 0.013 0.33 0.33 0.52 0.20 0.00 0.85 0.85 0.47 20.00 4.12 --1.65 0.85 0.47 N/A 15.00 4.55 1.82 4.56 3.72 40%
STR 18 STR 19 36 15 RCP 0.50 0.013 0.00 0.00 0.06 0.20 0.05 0.85 0.11 0.50 5.00 6.12 --0.33 0.96 0.47 0.40 15.40 4.52 2.06 4.56 3.72 45%
STR 19 STR 8 50 15 RCP 0.50 0.013 0.06 0.06 0.14 0.20 0.00 0.85 0.20 0.41 10.00 5.22 --0.43 1.16 0.46 0.16 15.56 4.50 2.42 4.56 3.72 53%
Structure
Pipe Data Pipe AnalysisContributing Watershed DataInlet Watershed Data
1/14/2025
115 N 17th AVENUE, BEECH GROVE, IN 46107 // 317.780.1555 // CROSSROADENGINEERS.COM PAGE 6 of 6
Section 4: Storm Inlet Calculations
Storm Inlet Summary
Storm inlets were placed throughout the site to ensure that sag inlets will be adequate to pass the
design 10-year flow and that the maximum depth of water shall not negatively impact adjacent
structures in the 50% clogged condition. Included in this section is a table comprising the grate
capacity calculations, data from the Neenah foundry company website, and a description of the
grate.
The weir equation was used when depth of flow is less than 4” and the orifice equation was utilized
for depths 4” or greater.
The weir equation is as follows: Q = 3.3P(h)1.5
Where: P = perimeter of the grate; h = head above the casting; Q = Capacity
The orifice equation is as follows: Q = 0.6A(2gh)0.5
Where: A = open area of the grate; h = head above the casting; g = 32.2 ft/sec2
STR # Q (cfs) Casting depth (in)
STR 1 1.23 R-3287-10V 3.2
STR 2 0.66 R-3287-10V 2.1
STR 3 0.53 R-3287-10V 1.8
STR 4 1.01 R-1878-A9G 1.8
STR 5 0.82 R-1878-A9G 1.6
STR 6 0.93 R-1878-A9G 1.7
STR 7 1.13 R-1878-A9G 1.9
STR 8 1.17 R-1878-A9G 2.0
STR 9 2.17 R-1878-A9G 3.0
STR 10 0.51 R-3287-10V 1.8
STR 11 1.62 R-1878-A9G 2.5
STR 12 0.76 R-1878-A9G 1.5
STR 13 2.44 R-1878-A9G 3.2
STR 15 1.78 R-1878-A9G 2.6
STR 16 1.01 R-1878-A9G 1.8
STR 17 1.65 R-4215-C 2.4
STR 18 0.33 R-3287-10V 1.3
STR 19 0.43 R-1878-A9G 1.0
Pond Report 3
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2024 Tuesday, 01 / 14 / 2025
Pond No. 1 - Wet Pond (Unrestricted)
Pond Data
Contours -User-defined contour areas. Average end area method used for volume calculation. Begining Elevation = 796.00 ft
Stage / Storage Table
Stage (ft) Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cuft)
0.00 796.00 62,984 0 0
1.00 797.00 67,631 65,308 65,308
2.00 798.00 72,468 70,050 135,357
3.00 799.00 77,405 74,937 210,294
4.00 800.00 82,443 79,924 290,218
5.00 801.00 87,581 85,012 375,230
6.00 802.00 92,820 90,201 465,430
Culvert / Orifice Structures Weir Structures
[A] [B] [C] [PrfRsr] [A] [B] [C] [D]
Rise (in)= 12.00 12.00 0.00 0.00
Span (in)= 12.00 12.00 0.00 0.00
No. Barrels = 1 1 0 0
Invert El. (ft)= 796.00 796.00 0.00 0.00
Length (ft)= 100.00 0.00 0.00 0.00
Slope (%)= 0.31 0.00 0.00 n/a
N-Value = .013 .013 .013 n/a
Orifice Coeff.= 0.60 0.60 0.60 0.60
Multi-Stage = n/a Yes No No
Crest Len (ft)= 0.00 0.00 0.00 0.00
Crest El. (ft)= 0.00 0.00 0.00 0.00
Weir Coeff.= 3.33 3.33 3.33 3.33
Weir Type = --- --- --- ---
Multi-Stage = No No No No
Exfil.(in/hr)= 0.000 (by Contour)
TW Elev. (ft)= 0.00
Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s).
0.00 1.00 2.00 3.00 4.00 5.00 6.00
Stage (ft)
0.00 796.00
1.00 797.00
2.00 798.00
3.00 799.00
4.00 800.00
5.00 801.00
6.00 802.00
Elev (ft)
Discharge (cfs)
Stage / Discharge
Total Q
Pond Report 5
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2024 Tuesday, 01 / 14 / 2025
Pond No. 3 - Wet Pond (Over-detained)
Pond Data
Contours -User-defined contour areas. Average end area method used for volume calculation. Begining Elevation = 796.00 ft
Stage / Storage Table
Stage (ft) Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cuft)
0.00 796.00 62,984 0 0
1.00 797.00 67,631 65,308 65,308
2.00 798.00 72,468 70,050 135,357
3.00 799.00 77,405 74,937 210,294
4.00 800.00 82,443 79,924 290,218
5.00 801.00 87,581 85,012 375,230
6.00 802.00 92,820 90,201 465,430
Culvert / Orifice Structures Weir Structures
[A] [B] [C] [PrfRsr] [A] [B] [C] [D]
Rise (in)= 12.00 3.00 0.00 0.00
Span (in)= 12.00 3.00 0.00 0.00
No. Barrels = 1 1 0 0
Invert El. (ft)= 796.00 796.00 0.00 0.00
Length (ft)= 100.00 0.00 0.00 0.00
Slope (%)= 0.31 0.00 0.00 n/a
N-Value = .013 .013 .013 n/a
Orifice Coeff.= 0.60 0.60 0.60 0.60
Multi-Stage = n/a Yes No No
Crest Len (ft)= 0.00 0.00 0.00 0.00
Crest El. (ft)= 0.00 0.00 0.00 0.00
Weir Coeff.= 3.33 3.33 3.33 3.33
Weir Type = --- --- --- ---
Multi-Stage = No No No No
Exfil.(in/hr)= 0.000 (by Wet area)
TW Elev. (ft)= 0.00
Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s).
0.00 0.06 0.12 0.18 0.24 0.30 0.36 0.42 0.48 0.54 0.60
Stage (ft)
0.00 796.00
1.00 797.00
2.00 798.00
3.00 799.00
4.00 800.00
5.00 801.00
6.00 802.00
Elev (ft)
Discharge (cfs)
Stage / Discharge
Total Q
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2024 Tuesday, 01 / 14 / 2025
Hyd. No. 1
Offsite Basin(s)
Hydrograph type = SCS Runoff Peak discharge = 47.33 cfs
Storm frequency = 10 yrs Time to peak = 12.00 hrs
Time interval = 2 min Hyd. volume = 123,435 cuft
Drainage area = 13.780 ac Curve number = 86
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 10.00 min
Total precip. = 3.83 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
1
0 2 4 6 8 10 12 14 16 18 20 22 24 26
Q (cfs)
0.00 0.00
10.00 10.00
20.00 20.00
30.00 30.00
40.00 40.00
50.00 50.00
Q (cfs)
Time (hrs)
Offsite Basin(s)
Hyd. No. 1 -- 10 Year
Hyd No. 1
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2024 Tuesday, 01 / 14 / 2025
Hyd. No. 1
Offsite Basin(s)
Hydrograph type = SCS Runoff Peak discharge = 93.32 cfs
Storm frequency = 100 yrs Time to peak = 12.00 hrs
Time interval = 2 min Hyd. volume = 250,078 cuft
Drainage area = 13.780 ac Curve number = 86
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 10.00 min
Total precip. = 6.46 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
6
0 2 4 6 8 10 12 14 16 18 20 22 24 26
Q (cfs)
0.00 0.00
10.00 10.00
20.00 20.00
30.00 30.00
40.00 40.00
50.00 50.00
60.00 60.00
70.00 70.00
80.00 80.00
90.00 90.00
100.00 100.00
Q (cfs)
Time (hrs)
Offsite Basin(s)
Hyd. No. 1 -- 100 Year
Hyd No. 1
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2024 Tuesday, 01 / 14 / 2025
Hyd. No. 3
Unrestricted Scenario
Hydrograph type = Reservoir Peak discharge = 1.677 cfs
Storm frequency = 10 yrs Time to peak = 18.13 hrs
Time interval = 2 min Hyd. volume = 118,082 cuft
Inflow hyd. No. = 1 - Offsite Basin(s) Max. Elevation = 797.10 ft
Reservoir name = Wet Pond (Unrestricted) Max. Storage = 78,831 cuft
Storage Indication method used.
2
0 10 20 30 40 50 60 70 80 90 100
Q (cfs)
0.00 0.00
10.00 10.00
20.00 20.00
30.00 30.00
40.00 40.00
50.00 50.00
Q (cfs)
Time (hrs)
Unrestricted Scenario
Hyd. No. 3 -- 10 Year
Hyd No. 3 Hyd No. 1 Total storage used = 78,831 cuft
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2024 Tuesday, 01 / 14 / 2025
Hyd. No. 5
Over-detained Scenario
Hydrograph type = Reservoir Peak discharge = 0.279 cfs
Storm frequency = 10 yrs Time to peak = 24.13 hrs
Time interval = 2 min Hyd. volume = 71,367 cuft
Inflow hyd. No. = 1 - Offsite Basin(s) Max. Elevation = 797.66 ft
Reservoir name = Wet Pond (Over-detained) Max. Storage = 111,643 cuft
Storage Indication method used.
4
0 10 20 30 40 50 60 70 80 90 100
Q (cfs)
0.00 0.00
10.00 10.00
20.00 20.00
30.00 30.00
40.00 40.00
50.00 50.00
Q (cfs)
Time (hrs)
Over-detained Scenario
Hyd. No. 5 -- 10 Year
Hyd No. 5 Hyd No. 1 Total storage used = 111,643 cuft
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2024 Tuesday, 01 / 14 / 2025
Hyd. No. 3
Unrestricted Scenario
Hydrograph type = Reservoir Peak discharge = 3.052 cfs
Storm frequency = 100 yrs Time to peak = 14.43 hrs
Time interval = 2 min Hyd. volume = 243,841 cuft
Inflow hyd. No. = 1 - Offsite Basin(s) Max. Elevation = 798.42 ft
Reservoir name = Wet Pond (Unrestricted) Max. Storage = 166,859 cuft
Storage Indication method used.
7
0 8 16 24 32 40 48 56 64 72 80 88 96
Q (cfs)
0.00 0.00
10.00 10.00
20.00 20.00
30.00 30.00
40.00 40.00
50.00 50.00
60.00 60.00
70.00 70.00
80.00 80.00
90.00 90.00
100.00 100.00
Q (cfs)
Time (hrs)
Unrestricted Scenario
Hyd. No. 3 -- 100 Year
Hyd No. 3 Hyd No. 1 Total storage used = 166,859 cuft
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2024 Tuesday, 01 / 14 / 2025
Hyd. No. 5
Over-detained Scenario
Hydrograph type = Reservoir Peak discharge = 0.406 cfs
Storm frequency = 100 yrs Time to peak = 24.17 hrs
Time interval = 2 min Hyd. volume = 111,100 cuft
Inflow hyd. No. = 1 - Offsite Basin(s) Max. Elevation = 799.27 ft
Reservoir name = Wet Pond (Over-detained) Max. Storage = 232,080 cuft
Storage Indication method used.
8
0 10 20 30 40 50 60 70 80 90 100
Q (cfs)
0.00 0.00
10.00 10.00
20.00 20.00
30.00 30.00
40.00 40.00
50.00 50.00
60.00 60.00
70.00 70.00
80.00 80.00
90.00 90.00
100.00 100.00
Q (cfs)
Time (hrs)
Over-detained Scenario
Hyd. No. 5 -- 100 Year
Hyd No. 5 Hyd No. 1 Total storage used = 232,080 cuft
Hydraflow Rainfall Report 9
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2024 Tuesday, 01 / 14 / 2025
Return Intensity-Duration-Frequency Equation Coefficients (FHA)
Period
(Yrs)B D E (N/A)
1 0.0000 0.0000 0.0000 --------
2 241.5741 28.3001 1.1283 --------
3 0.0000 0.0000 0.0000 --------
5 0.0000 0.0000 0.0000 --------
10 337.4067 28.7001 1.1400 --------
25 0.0000 0.0000 0.0000 --------
50 0.0000 0.0000 0.0000 --------
100 463.3860 28.0001 1.1234 --------
File name: Hydraflow Carmel.IDF
Intensity = B / (Tc + D)^E
Return Intensity Values (in/hr)
Period
(Yrs) 5 min 10 15 20 25 30 35 40 45 50 55 60
1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
2 4.63 3.95 3.44 3.04 2.72 2.46 2.24 2.06 1.90 1.76 1.64 1.54
3 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
5 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
10 6.12 5.23 4.55 4.02 3.60 3.25 2.96 2.72 2.51 2.33 2.17 2.03
25 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
50 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
100 9.12 7.78 6.77 5.99 5.36 4.84 4.41 4.05 3.74 3.47 3.24 3.03
Tc = time in minutes. Values may exceed 60.
Rainfall Precipitation Table (in)
Precip. file name: R:\Active\MI Homes\Kephart Properties\DOC\DRAINAGE\SECTION 3 CALCS\HYDRAFLOW\Sec. 3 & 4 WQ.pcp
Storm
Distribution 1-yr 2-yr 3-yr 5-yr 10-yr 25-yr 50-yr 100-yr
SCS 24-hour 0.00 2.66 0.00 0.00 3.83 0.00 0.00 6.46
SCS 6-Hr 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Huff-1st 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Huff-2nd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Huff-3rd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Huff-4th 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Huff-Indy 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Custom 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00